Fuel Starvation or not ?

[elfman]

Hi 

I have a problem that is very tricky to pin down.

The car is a Volvo Amazon 1.8 with a Zenith Carb ( I rather SU's but cant fine a pair yet)

I bought the car in Stowmarket and drove it nearly 300 miles home to Swansea and it ran like a watch, used it for a few runs, took it to work etc and all was perfect a joy to drive.

I went on Holidays for 3 weeks and by the time i ran it again, probably well over a month the problem started.

Its starts ok and seems to run fine until  you try and pull a hill on a dual or motorway....then its feels as if its running out of fuel, it misses and you have to back off etc...

It will climb short steep hills no problem at all and runs on the flat ok until you hit about 75 mph....then the same problem returns.

I changed the fuel filter, as it was dirty and it was about 80% better, then I blew the fuel lines back and it seemed as if it was back to normal

Went out today and it was as bad as ever,,,,had to stop in a lay-by on the way home, but i revved it hard re-started it and was better on the way back.

I think the fuel tank is dirty,, i spoke Burlen the carb people and they don't think its the carb as it would be worse lower down the rev range, the smaller jets would be blocked before the larger ones ...

I have also checked the plugs, points, lead,s distributer cap, and added fresh fuel etc etc...( I have not changed the Condencer yet )

So apart from not running it for a month the problem came out of no where ?

I was thinking of removing the mechanical fuel pump and seeing if that's the problem  by testing & timing the flow, then the next stop is stripping the carb and i know nothing about Zenith carbs....

So any ideas ?

[jonsey]

Sounds to me like something could be blocking the pick up in the tank or even the tank not venting properly.

[elfman]

I was thinking the same, I remember years ago my Dad used to have a simular problem with a Viva and used to put a foot pump on the fuel line and blow the crud back and clear the line.... hence mine went better when I did the same..

I will double check the breather but then I think i will have to drop the tank, flush and reline it..

[slater]

I think you've guessed right. Rusty tank.. You could try bypassing the mechanical pump with a cheap electric pump and see if it makes any odds.

[elfman]

Good idea ill see if i have an old Mini Pump floating around.. i don't like mechanical pumps as they are a pain to check if working ok, but i have found some info on how to check them.
Cheers for your advice it all helps.

[gtviva]

Can you put an inline see through type filter near the carb? you will then be able to see how much rubbish its pulling up, if you think a jet is blocked a good tip is when the engine is running get a big cloth and roll it into a ball and cover the intake of the carb making an air tight seal, works wonders for clearing jets

Not sure what Zenith carb you have but its probably got an accelerator pump diaphragm which will be passed its best

[andyf]

I had a similar thing with misfiring under load, same as you, showing up on steep hills. I chased a fuel issue but it turned out to be a spark plug breaking down under load- so when you say you checked them, did you actually swap them out?

[elfman]

I'm going to replace the plugs points and condense etc but I am doing things one at a time as I want to know exactly what the problem was. I still think it's fuel related at it did disappear for one journey when I blew the fuel line out.
Worse thing is it feels ok until I climb a long hill, so have to drive a few miles on to the motorway or 12miles to a dual to find a suitable hill !!
Many thanks for all your advice 😊 I'm working my way through them.

[ChasR]

Do you have a heat shield between the carb and the exhaust manifold?

Without this, the fuel will boil quite readily in the float chamber once the fuel is warm and cause some major hot starting issues.

How dirty is your fuel filter?

If you fit a mechanical pump you'd be wise to fit one that is rated to the pressure the carb can take or fit a half decent pressure regulator in line. Bar the SU-type pumps, many Facets tend to overpressurise carbs and in some cases can present more issues.

Good call on checking the ignition system, especially if still on points. As you already know:
-Check the gap or preferably the dwell angle via a dwell meter if you can
-Check the rotor arm on continuity
-Check/change the plugs and only buy them from a known source, not whoever is the cheapest (I've been stung here before on a similar misfiring issue.
-Ensure the advance is working as it should.

[scimjim]

I had similar symptoms on the way back from Le Mans one year - turned out to be fake rubber fuel pipe breaking down internally (probably due to the increased ethanol content). Replaced all hoses and the problem disappeared.

[elfman]

Thanks again for your advice its much appreciate.

I don't think its a heat problem as the Zenith carb sticks up in the air well away from any real heat and it was driven 300 miles home at the end of the summer with no problem, its been a problem over the colder winter months..

I have left is for a few weeks as its not used much in the Winter and i have a much bigger rebuild project on the go.

But as a few of you have said i am getting all new points, plugs, condencer, cap rotar arme etc ready for a complete overall. plus I have found some instruction how to measure the mechanical pump to see if its supplying the correct amount of fuel...its all standard so its easy to measure.

Plus when its a bit warmer i am going to get a relining kit for the tank as the new filter is getting dirty again, and i will replace the rubber lines at the same time....never thought of them ! but it might well be considering the ethonol in the fuels these days. Plus i cant see a tank breather so i will make sure it has one in the future.

It will end up on twin SU's electronic ignition etc but I would like to solve it first as its bugging me.

Thanks again

[kevins]

Sounds like the gauze filter most cars have on the pick up pipe in the tank, our minor did the same, I had to use an endoscope to see the mass of crud stuck around it.

[mk2cossie]

You say it has been happening in the colder weather, is it simply just the carb icing up?

My friend had a fairly lairy A series mini with a single SU carb, and the exhaust was wrapped on that, and that suffered quite a bit with the carb icing up

[elfman]

Sorry should have made it clearer its not freezing weather but from November on after I left the car sitting for a month....I'm sure its nothing to do with the carb getting too hot or cold. But I also don't like the Zenith carb, once its all sorted I'm swapping over to twin SU's..

I used to get twin SU's freeze on a Mini and it usually manifested itself with them sticking wide open, quiet entertaining when driving through a quiet Welsh Village full of snow !!

Enderscope sounds a good idea as i have a friend who works in a Garage might be able to borrow one for a good look inside the tank...i think its the ethanol dislodging the crud in the old tank and also doing its worst on the rubber hoses....

I'm back to welding on my other project at the moment, at least it keeps me warm... but thanks to all the tips i have plenty to go through on the Volvo once it gets a bit warmer.

Thanks again for all your help and advice i genuingly appreciate every comment.

[elfman]

I have finally got to taking the tank out, easy job as it happens and I drained out fuel.
Its was full of rust and cr*p you could hear it sloshing around in the tank...
I also could see a potential problem that might have added to the fuel starvation, the pickup is well over an ins from the bottom of the tank, and its a wide shallow tank so the fuel might have moved to the rear of the tank as the car hit a long hill !!!
So between the rubbish in the tank and the pick i think both added to the problem.
I now have another problem to deal with, after cleaning the top of the tank i see it has number of pin holes because of rust...all nicely painted over !! the bottom of the tank seems fine with no rust at all but i can feel the rust on the inner top of the tank
I know you can get a Por 15 tank liner kit but has anybody used one before ? (any feedback would be appreciated) I worked it out it will cost close to £100 to line, fill and repaint the Tank etc, of should i get a new one for £235..?
I do plan on keeping the car.
I have a pair of SU's cleaned and ready to fit so I m trying to find a second hand head to work on ready to fit at the same time, does anybody know a good chap for gas flowing a Volvo Amazon head ?

[mk2cossie]

If it is a keeper, I would plump for the new tank option.
It may be twice the price of the tank lining kit, but can you guarantee that will work and how long will it last with a pin holed tank anyway

At least new is more or less fit and forget

[elfman]

Thats true if i planned on selling i might have done a repair but as I'm keeping it, a new tank is probably the best bet plus the pick up might be deeper/lower in the new tank..

[elfman]

Apologies for not getting back to you all.
I finally sorted the problem.
I lifted the tank out after removing the fuel and as i drained it I could see the crud in the petrol. I could also see the pickup was at least an 1" from the bottom of the tank...so going up hill on low fuel could have been a factor..it was also full of rust and gunk.
The top of the tank was also peppered with small holes but covered in paint and filler...nice!
I did look at relining the tank but as it was only double the price for a new one i bit the bullet and got a new tank from Brookhouse, it was here in a few days and was a very nice bit of kit and fitted perfectly..
I filled it with clean fuel went for a run and although it felt better the problem was still there..Grrrrr
I checked the pump and carb again,,,,still the same.
I then bought a set of new plugs, points and New condensor... ( could not get the exact new leads as out of stock)
It started in a flash took it for a run and it felt like a new car, and run like a watch.
So not sure if it was the condenser or the plugs as some of you correctly said, but its now fixed.
Many thanks for all your advice as i could have sworn it was a fuel problem but at least I know have a nice clean tank minus the holes and dirt.
I can now get on with making sure the rest of the car is good and start to get it as I want, some of the wiring is a mess then I can start lowering it and fitting some nice wheels etc.

[ChasR]

Great to hear about this and it's nice to see that the problem is fixed.